Australia's koalas are under threat from two different diseases, one of which is familiar to humans. Koalas are frequently being infected with chlamydia -- and it may decimate the population. But new research, and a new vaccine, gives hope they may be saved.

Australia's koala population has been hit hard by two rapidly spreading diseases: chlamydia (a sexually transmitted infection) and a retrovirus similar to HIV. Scientists are working to develop vaccines, while lay citizens help care for sick koalas.

Australia's koala population has been hit hard by two rapidly spreading diseases: chlamydia (a sexually transmitted infection) and a retrovirus similar to HIV. Scientists are working to develop vaccines, while lay citizens help care for sick koalas.

Australia's koalas are under threat from two different diseases, one of which is familiar to humans. Koalas are frequently being infected with chlamydia -- and it may decimate the population. But new research, and a new vaccine, gives hope they may be saved.